Phase II results disclosed June 17 with bapineuzumab, the beta-amyloid buster from Elan and Wyeth, showed the monoclonal antibody missed statistical significance in the primary efficacy endpoints.

But data from the 240-patient trial left Wall Street cautiously pleased, as the two firms hailed strong efficacy and acceptable safety in AD patients who do not carry the Apolipoprotein E4 gene, which totals between 40 percent and 70 percent of the AD population.

In non-carriers of the ApoE4 allele, post-hoc analyses showed statistically significant and clinically meaningful benefits on efficacy endpoints such as the Alzheimer's Disease Assessment Scale, the Neuropsychological Test Battery, the Mini Mental State Examination and the Clinical Dementia Rating-Sum of Boxes.

A favorable directional change was seen on the Disability Assessment Scale for Dementia (DAD), too, though it was not statistically significant.

Other firms with AD drugs in the works believed Phase II trials too small to show value in gauges such as ADAS-cog or NTB. Lilly, for example, used less extensive testing in Phase II work with its gamma secretase inhibitor, saving fuller evaluations for Phase III (¹ Also see "Five Late-Stage Products In Lilly’s Pipeline Could Launch By End Of Decade" - Pink Sheet, 25 September, 2007.).

The preliminary peek at MRI results with bapineuzumab, also in non-carriers of ApoE4, showed less loss of brain volume among treated patients versus placebo, a statistically significant finding.

Smaller increases in ventricular volume showed up in treated patients compared to placebo patients, too, but the result missed statistical significance.

"Takeover speculation should increase on today's news, given the interest larger pharma companies have shown in expanding their biologics business in general and their focus on AD in particular," wrote Credit Suisse analyst Catherine J. Arnold in a June 17 research note.

Elan and Wyeth started a Phase III program with bapineuzumab in December. Trials in the U.S. and Europe could enroll around 4,000 patients, as investigators watch for safety signals that could jeopardize the work. The firms' earlier AD drug, AN1792, ran into vasogenic-edema side effects.

The Phase III trials were designed with findings from the Phase II study in mind.

"Until today, I largely regarded the Alzheimer's drug as gravy," said Ken Kam, portfolio manager of the Masters 100 Fund.

Elan has been his mutual fund's largest holding since June 2005, before the multiple sclerosis drug Tysabri (natalizumab) returned to the market. It had been withdrawn for safety concerns, and since has been cleared by FDA for Crohn's disease as well.

"We don't think the sales ramp in Tysabri has really started yet," Kam said.

In AD, Kam called bapineuzumab "the most hopeful thing there is" for patients without the ApoE4 marker.

- Randall Osborne (r.osborne@elsevier.com)

Elan, Wyeth’s Bapineuzumab Data Mixed In Phase II For AD

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